1. Field of the Invention
The present invention relates to an information signal controlling system having a data holding device which is removably attachable to an apparatus and which holds various kinds of data.
2. Description of the Related Art
Various methods have conventionally been considered in order to combine, as by superimposition, an image such as a character, a symbol or a specific graphic image with a video signal to be recorded on a recording medium for the purposes of enhancing image effects or in order to superpose background music or effect sound on an audio signal to be recorded on the recording medium, when the video or audio signal obtained by photography using a video camera or the like is to be recorded on the recording medium.
One method of combining a different image signal with a video signal obtained by photography makes use of, for example, a so-called character generator.
This method utilizes an arrangement consisting of a pattern ROM (read-only memory) which stores patterns such as characters and symbols to be displayed, a register which stores the kind of character to be displayed at each display position, and a reading part for reading the contents of the pattern ROM that correspond to the contents of the register and combining the read contents with a video signal, in accordance with horizontal and vertical sync signals. When a character is to be displayed, the kind of character to be displayed is written into a register for a desired display position by a microcomputer or the like.
Another method is to convert an image signal obtained by imaging using a video camera or the like into a digital image signal of the order of one to several bits by an A/D converter, to store the digital image signal in a memory for each display pixel, to sequentially read the contents stored in the memory in accordance with horizontal and vertical sync signals, and to combine the read contents, as a different image signal, with a video signal separately obtained by imaging using the video camera.
Still another method utilizes an arrangement consisting of a graphic memory having an address corresponding to each pixel position on a picture, a microcomputer for writing data at a display address among the addresses within the graphic memory, and a reading circuit for reading the contents stored in the graphic memory. In this method, the contents stored in the graphic memory are read in accordance with horizontal and vertical sync signals, and the read contents are combined as a different image signal with a video signal obtained by photography using a video camera.
A method of combining a different audio signal with an audio signal recorded during photography using a video camera is to prepare a device for generating an audio signal, such as a record player, a tape player or an electronic sound generator, and combine, as by a mixing amplifier, the audio signal generated by such a device with an audio signal recorded during or after photography.
However, as described above there is the disadvantage that the image combining device, which is needed when a different image signal is to be combined with a video signal obtained by photography is different from the sound combining device needed when a different audio signal is to be combined with a recorded audio signal. In addition, since a number of connecting wires are needed for connecting those devices, the connection between the devices and their operation become complicated with the result that an erroneous operation easily occurs and operability is impaired.